Gary John Dorrien (born March 21, 1952) is an American social ethicist and theologian. He is the Reinhold Niebuhr Professor of Social Ethics at Union Theological Seminary in the City of New York and Professor of Religion at Columbia University, both in New York City, and the author of 18 books on ethics, social theory, philosophy, theology, politics, and intellectual history. Prior to joining the faculty at Union and Columbia in 2005, Dorrien taught at Kalamazoo College in Michigan, where he served as Parfet Distinguished Professor and as Dean of Stetson Chapel.